The present invention relates to the technical field of solar cells, and particularly, to a front-side conductive paste for a crystalline silicon solar cell, a preparation method therefor, and a solar cell.
Solar energy is an inexhaustible and clean energy source. With the depletion of non-renewable energy sources such as coal and petroleum, the development and utilization of solar energy has become a hot spot. Solar cells developed based on this idea are an important means of utilizing solar energy. At present, the industrialized crystalline silicon solar cell has become a model for use of solar cells.
Cell chip is a core component in the crystalline silicon solar cell. In order to collect and guide the current generated under illumination, an electrode needs to be fabricated respectively on each of a front side and a back side of the cell chip. There are various methods available for manufacturing electrodes. Among them, screen printing and co-sintering are a currently most common production process. For example, in the manufacture of front-side electrodes, a conductive paste is applied to a silicon cell chip by screen printing, and a front-side electrode is formed on the front side of the silicon cell chip by sintering. The sintered front-side electrode of the crystalline silicon solar cell needs to be firmly adhered onto the silicon cell chip, has narrow and high grid lines and small light shielding area, and is easy to be soldered. The conductive paste for the front-side electrode of the silicon solar cell is required to have the ability to penetrate a silicon nitride anti-reflective film during the sintering process, to form a good ohmic contact with the silicon cell chip.
A common front-side conductive paste for the crystalline silicon solar cell contains a silver powder, an oxide etching agent, and an organic carrier, and the conductive paste is printed on the solar cell followed by sintering to form a front-side electrode. During the sintering process, an oxide etching agent in the conductive paste etches and penetrates an anti-reflective insulating layer such as silicon nitride, titanium oxide, aluminum oxide, silicon oxide, or silicon oxide/titanium oxide on the front side or the side of irradiation of the crystalline silicon solar cell, so that the silver powder is brought into contact with the substrate of the crystalline silicon solar cell to form a front-side electrode. In order to increase the conversion efficiency of the silicon solar cell chip, the sheet resistance of the solar cell chip is increased the conventional front-side conductive paste and the oxide etching agent used cannot well etch the anti-reflective insulating layer on the surface of the silicon solar cell chip. As a result, the adhesion of the front-side electrode formed on solar cell chip surface is decreased, and the contact resistance between the front-side electrode formed and the surface of the silicon solar cell chip is high, thus not only affecting the photoelectric conversion efficiency of the silicon solar cell chip but also the reliability of the solar cell chip in the field application.